Most therapeutic regimens currently in use for sphincter preservation in anal cancer utilize combined radiation therapy and chemotherapy. To provide a basis for comparison with combined therapy results, an analysis was made of patients treated with external radiation therapy without chemotherapy.

Eighteen patients with squamous cell, basaloid, or cloacogenic carcinoma of the anal canal were treated with external radiation therapy between January 1, 1980, and December 31, 1989, with the goal of sphincter preservation and cure. Before radiation therapy, five patients had incisional biopsies, two underwent piecemeal removal of the tumor, three had excisional biopsies with positive margins, five had excisional biopsies with negative margins, and three had excisional biopsies with unknown margins. All patients received 45 to 50 Gy in 25 to 28 fractions to the pelvis and perineum, and 16 of the 18 received an additional boost to the primary site to bring the total dose to 55 to 67 Gy in 30 to 38 fractions.

With follow-up of 2.5 to 11.2 years in surviving patients, 5-year projected survival and freedom from local recurrence were 94% and 100%, respectively. Two patients required a temporary colostomy because of treatment complications. No patient required a permanent colostomy or had permanent loss of anal sphincter function as a result of local recurrence or complications.

These results, combined with others, suggest that external radiation therapy without chemotherapy is an acceptable alternative to combined radiation therapy and chemotherapy in the management of anal cancer.